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**mack** · 11-06-2012, 04:07 PM

Carbs

I don't know anything about swapping different styles of carbs for these bikes. However, I can send you down a set of XS carbs (spotless inside and out) to try. I can also send you a handfull of jets that you can experiment with to find the right combo. Once you get them figured out you can send my stuff back.

**WMarshy** · 11-06-2012, 04:20 PM

Just do a search for "ZRX" and it should return a lot of info on it. They are probably the #1 recommended carb swap option. The reason I say that is because I haven't heard much talk about other options (not saying there isn't). ZRX carbs are bolt on with two exceptions. A hole needs to be drilled for the vac advance and jetting needs to be changed, otherwise they are bolt on because the spacing fits. Not exactly sure what needs to be done with the throttle cable...

If money is no option then Im sure you could get a pair of Keihin FRC carbs but they will run you 1-2K for a pair.

http://www.youtube.com/watch?v=bGr0yksH0eY

http://www.youtube.com/watch?NR=1&v=...ture=endscreen

**MPittma100** · 11-06-2012, 04:33 PM

Stock Carbs

I suggest using the stock setup with stock carbs. If you have changed the exhaust, maybe some different jets. Other carbs will be other problems.

Like it or not, bike is worth more in the long run being as close to stock as possible.

MP

**DGXSER** · 11-06-2012, 05:15 PM

If your looking for the best option, with your highly modified intake and exhaust setup, I would suggest a fuel injection set up. It will cost a pretty penny, but it is very tunable.

**airborneXS** · 11-07-2012, 02:45 AM

fuel injection is something down the line...i plan on fuel injection and a turbo setup one day....i dont plan on ever selling this bike...lol

**TADracer** · 11-07-2012, 08:08 AM

I can recommend the ZRX carbs.

Here is a recent PM I recently received and my response.

I have been tinkering with my SF since I bought it in 1980 and this is the best upgrade I have ever done. Once you tune them to your machine your carb troubles will virtually disappear.

-------
Originally Posted by Nubian
is that zxr-1200 a direct fit with no mods?
Also why is it better than xs1100 stock carbs?
Ed

Originally Posted by TADracer
Its not 100% plug-N-Play but close. First, the carb spread is slightly different than the stock Mikunis however they do pop right into the existing manifolds. I have pod air filters so I am not sure about how the stock airbox fits but I know the carbs are a bit shorter than the stock ones so you might have to move that forward a half inch or so.

If your model requires a metered vacuum tap for a vacuum advance then you will have to make that but it is not terribly hard to do. I have a post here showing how I did it. Search ZRX Carbs and you should find that along with some other pictures.

The throttle cable will need a slight massage since the Keihin carbs are a push/pull arrangement. But, the springs on the carbs are plenty strong enough to snap the throttle closed so a pull only cable will work. I removed about 1/2" of the outside sheath from the carb end of the cable and then fashioned a small grommet to fit into the cable holder on the carbs. All it is is a small brass fitting I filed to fit the condition. BTW, I find that when removing the rack of carbs it is now easier to leave the throttle cable attached to the carbs, unhook it at the handlebar and remove the cable with the carbs. And with the pod filters the carbs can literally be out and on the table in less than five minutes.

You will also need to install a choke cable but that is very easy to do with a generic cable from any auto parts store.

You will probably need to re-jet to fit your bike's mofdifications. Jets are cheap and easy to get from Jets-R-Us.

All this sounds like alot but in actuality it only took a few hours to get them ready to pop into place.

Now, why are they better? Well, they are 25 year newer technology for starters. They use light-weight slides which makes the midrange more crisp. The pilot circuit is much better so they idle much more steady and as an added bonus, they have an external idle speed adjuster that can be worked anytime, even at a stop light with you left hand. No more removing the seat and reaching up between the #2&3 carbs with long screwdrivers to adjust idle speed. They have a deceleration valve that meters in a small amount of fuel on deceleration that will get rid of that annoying popping that sometimes happens with running a more lean pilot jet (the Mikunis like those on the rich side). The bowl/float/needle valve arrangement is leaps and bounds better plus the bowls seal with an o-ring instead of a gasket. And the really important part, they are larger (36mm instead of 30mm for the Mikunis), they hold synchronization and idle mixture adjustments better than the Mikunis. Also, when you do make an adjustment, the adjustment is much more accurate than the Mikunis are and fuel mileage is usually better.

The performance is there for sure and you will definately notice it on your first time out. I have tinkered with exhaust, head porting, ignition mods, air filter mods, cam timing etc. and I can say for certain that this modification will give you alot for the $ invested. It is by far the best modification I have ever done on my XS11.

Hope this helps ya.
Mike

**IanDMacDonald** · 11-07-2012, 10:33 AM

You know, all of these posts are great, but, nobody is asking if AirborneXS has tried going back to smaller jets, and tried doing things right. It's cool that he wants to throw different carbs on because the Mikuni's are giving him a headache from his current setup, but, to me it's also a quitters mentality. This stuff takes patience. Before I learned about air/fuel mixtures (Stoichiometry) at school, I ended up taking my bike to a shop that charged me $400 to do something that turned out to be nothing more than Main jets that were too big, and cheap pods that were blocking the intake holes of the carbs. AFR is a science that requires patience. I am one of the biggest novices when it comes to jetting carbs and troubleshooting. But, I get the manual out, I search the forums, etc., to get the answers I need.

Here is my suggestion once again: start with stock carb arrangement, and go up. I remember some clown on here when I first started with my 750 (before I knew of the Triple's site) with pods, suggested that I jump to a 145 main, when the stock jets were 130's. WTF??? Do yourself a favor and do not throw in the towel so quick. Try things out. Check your plus after each switch of the jets. After every switch of the jets, you must re-tune, and re-sync. Give it a try 'ol chap.

**IanDMacDonald** · 11-07-2012, 10:34 AM

Whoops, did not see MPittmans post, lol. So, I guess people are reiterating what I have been saying . . .

**airborneXS** · 11-07-2012, 02:40 PM

I cant use the stock setup, as when i got the back the stock pipes and airbox were hacked beyond repair...i can try stock jetting, but i would have to buy some jets...

**DGXSER** · 11-07-2012, 02:45 PM

With your modified exhaust and POD filters, stock jetting is not going to be your answer. Depending on how much backpressure the exhaust you have provides, you may have ALOT of trouble finding the best setup. And even then, you may well have very poor performance in certain ranges.

There was a post recently of a video made by an exhaust or performance shop where they showed the effect of taking the backpressure out and how performance was changed, even with the best jetting they could tune to, the performance was not great in its best range, and suffered more in other ranges.

Honestly, I am not sure that the different carbs will overcome that problem, but they may perform better than stock ones, or not.

**airborneXS** · 11-07-2012, 03:49 PM

it should provide at least some decent backpressure...im not sure the equivalent of these baffles is to the oem exhaust...

on this page i used the short one...
http://4wheelonline.com/motorcycle/B....190644.760401

**rs2289** · 11-07-2012, 07:29 PM

This is actually a great topic. I am planning on pod filters and a custom exhaust as well in my rebuild. The exhaust I had was shot to holy heck and honestly I think I can build a short set similar to what airborneXS has built (with some differences) for a lot less than what the exhaust are going for on these babies.

Personally though, other then those mods, and different paint; my plan is to keep it stock over all. I was planning on just getting different sets of jets as they really don't cost that much and running some tests with them because I really don't know how much of a pressure change I will have.

From searching youtube videos of different custom builds, I know guys are running wide open pipes with success tuning and some minor popping on de-throttling. No different than an american built chopper. From what I can see they all run the stock carbs.

Technically, you can modify any 34mm CV carb into these things and make it work, but it will take some machining and a lot of know how to do it and make it work well.

So my vote is for different jet options on the original carbs.

**Rasputin** · 11-07-2012, 08:56 PM

Every bike I have worked on is the same story. I start with the carbs in the stock position. Then I tune to what the bike tells me it needs. I have tuned for overbore, 4 into 1 headers, 4 into 2 headers, Pods with or without said headers etc.
I find that using the stock setting as a starting point other members will advise what may be going on from there. If you start with larger jets etc just because the site has a jetting recommendation post or some "buddy" says so, you will chase your tail.
The bike will respond to any changes with how it runs at certain levels. How the bike accepts or rejects each change will tell you more. The plug read is one of the best diagnostic tools you have available and it is easy and cheap to do. Changing jets is also easy and fairly cheap. Do it right just once and the bike will pay you back in spades... until you make the next change.
Stock carbs will get you where you need to be on any 1100 when they are set up properly. No need to go to huge extremes to get it fueled correctly. The one thing I will say is that without back pressure on the exhaust they will never discover the true strength of an 11. While many will say their bike is a strong runner when posting on you tube... one must also consider how many PO's have given up and sold their bikes cause they really did not run right.
Here are the two best sites I know of for carb setting.

http://www.factorypro.com/tech/carbt...m_engines.html
http://oldmanhonda.com/MC/Rcarbs.html

I also am a firm believer that a throttle chop must be done. I prefer the high speed under load check myself but there are variations that will give similar results. If you do not have room or guts enough to do a high speed chop then look it up as nothing else will tell you the same story. If your main jets are set correctly the rest gets easier.
My plugs are a light brown at idle and the same at a 100 MPH. I get 45 - 48 MPG (imperial) all day long at 75 MPH. The bike will pick up the front wheel under roll on at about 4000 rpm in first gear. So Yeah I am happy I do it my way. To each his own but I would go back to a starting point every member can relate too. The tune from there.

**TADracer** · 11-08-2012, 08:11 AM

Everything Rasputin says is true. If you are making minor adjustments you always must start with some sort of starting point to work from and the stock settings would be a good place. However as you do modifications (especially those that cannot be reversed) your actual baseline settings (defined as balancing act) will change and those stock settings can be left behind once your new settings are established. And 'baseline' does not mean just carburetor settings, it means everything including timing, plug type and heat range, advance curve, valve lash.....everything. When you do wide ranging modifications finding a well balanced group of settings can be a hard thing to accomplish but once you do then WOW! IMHO the best way to establish new CARB jetting and adjustments to accomodate for modifications is to tune from the top down. That method is a true performance-based method and needless to say, make only one change at a time and write the results down.

I suggested the ZRX Keihin carb swap because Airborne said he was tired of dealing with the stock carbs. Been there, done that! I certainly do not look at switching to better carbs as a quitters attitude. The fact is my original Mikunis plain wore out complete with sinking floats, broken float arms, worn needles and emulsion tubes....so why not switch to newer technology? Either way, it is a matter of preference. When I put on the ZRX carbs I still tuned them from the top down just like in the FactoryPro link Rasputin put on his post. It is a bit of a pain to do but when done the performance is definately there.

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Carb ideas please....

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